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BUREAU OF MINES ^5^ 
INFORMATION CIRCULAR/1988 




Integrated Compartment-Machine 
Design for Low-Coal Shuttle Cars 



By John R. Battels, August J. Kwitowski, 
and William D. Mayercheck 



UNITED STATES DEPARTMENT OF THE INTERIOR 



Information Circular 9200 



Integrated Compartment-Machine 
Design for Low-Coal Shuttle Cars 



By John R. Bartels, August J. Kwitowski, 
and William D. Mayercheck 



UNITED STATES DEPARTMENT OF THE INTERIOR 
Donald Paul Hodel, Secretary 

BUREAU OF MINES 
T S Ary, Director 






Library of Congress Cataloging in Publication Data: 



Bartels, John R. 

Integrated compartment-machine design for low-coal shuttle cars. 

(Information circular; 9200) 

Bibliography: p. 18 

Supt. of Docs, no.: 128.27:9200. 

1. Mine railroads -Cars -Safety measures. 

I. Kwitowski, August J. II. Mayercheck, William D. III. Title. IV. Series: 
Information circular (United States. Bureau of Mines); 9200. 



TN295.U4 [TN342] 



622 s 



[622'. 334] 88-600147 



CONTENTS 



Page 



Abstract 1 

Introduction 2 

Project execution 2 

Evaluation criteria 2 

Cab-shuttle car concepts 3 

Determination of remote vision limitations 4 

Discussion of concepts 4 

Design considerations 10 

Design procedure 13 

Mockup and evaluation 16 

Changes resulting from mockup 17 

Conclusions 18 

References 19 

ILLUSTRATIONS 

1. Parallel end-driven shuttle car 5 

2. Parallel center-driven shuttle car 6 

3. Transverse end-driven shuttle car 7 

4. Bottom dump shuttle car 8 

5. Transversely mounted end-cab 9 

6. Vision-assist test 11 

7. Coal miner anthropometrics 12 

8. Compartment design 13 

9. Control layouts 14 

10. Selected control layout 15 

11. Computer-generated field of vision 15 

12. Shuttle car operator seat 16 

13. Joystick steering 17 

14. Final mockup 18 

TABLE 

1. Recommended control motions 12 



UNIT OF MEASURE ABBREVIATIONS USED IN THIS REPORT 


ft 


foot 


pet 


percent 


h 


hour 


y 


year 


in 


inch 







INTEGRATED COMPARTMENT-MACHINE DESIGN FOR LOW-COAL 

SHUTTLE CARS 

By John R. Bartels, 1 August J. Kwitowski, 1 and William D. Mayercheck 2 



ABSTRACT 

This Bureau of Mines report describes the development of a preliminary design for a novel, protected, 
cab-shuttle car for use in working seam heights down to 40 in. Because of the severe restrictions 
imposed by low-coal operation, Mine Safety and Health Administration (MSHA) regulations only require 
canopy protection on shuttle cars operating in seam heights of 42 in or greater. MSHA routinely grants 
variances for canopy use in seams 48 in high or less. The design was generated by giving the operator 
needs equal priority as related to machine performance parameters. Cab-shuttle car concepts that led 
to the recommended design are described, along with criteria and testing used to evaluate their potential 
effectiveness. 



Civil engineer. 

Supervisory physical scientist. 

Pittsburgh Research Center, Bureau of Mines, Pittsburgh, PA. 



INTRODUCTION 



Cabs and canopies installed on underground coal 
mining face equipment in use on high-coal equipment have 
established an impressive record of preventing fatal and 
nonfatal operator injuries. MSHA estimates that from 
January 1974 through December 1985, the protective 
structures kept 233 lives from being lost as a result of roof 
falls (2). 3 Unfortunately, the successful application of cabs 
and canopies has occurred almost exclusively in relatively 
high coal seams. A 1982 survey showed that for working 
heights below 48 in, only 27 pet of all face equipment had 
protective operator structures. For working heights below 
42 in, the percentage of equipment with cabs and canopies 
dropped to 2 pet (3). 

While the availability of protection in working heights 
below 48 in is low, the need for protection is high. For the 
2 yr period 1980 through 1981, there were a total of 2,212 
fatal and nonfatal equipment accidents in working heights 
below 48 in. It was estimated that 71 pet of these 
accidents could have been prevented had protective 
structures been employed (3). 

A problem with trying to provide workable cabs and 
canopies for face equipment used in seam heights below 
48 in relates to simple geometry. Insufficient space exists 
to (1) have the machine perform its intended functions, 
(2) station an operator and the controls, (3) insure 
adequate operator vision to key points on the machine and 
in the mine, (4) provide sufficient operator comfort for 



protracted work periods, and (5) provide structures that 
both protect the operator and do not significantly interfere 
with other requirements. The issue of protecting shuttle 
car operators from hazards becomes increasingly difficult 
with decreasing working height. 

Underground face equipment, such as continuous 
miners, roof bolters, face drills, etc., is usually much easier 
to equip with protective operator cabs than shuttle cars. 
These types of face equipment perform their functions 
primarily at one location; e.g., a continuous miner extracts 
coal at the face, while, because of its function, a shuttle car 
frequently travels through the working section. The tram 
rates of shuttle cars are also significantly higher than those 
of other face equipment. Current shuttle car designs tend 
to maximize tram clearances for tight spots in mine 
workings. 

The requirement for tram clearance is opposed by a 
primary goal in the shuttle car design - maximize the 
amount of cut coal transported from the face. An 
unfortunate effect is that space that should be used for 
operator, the controls, and a protective structure is 
sacrificed for increased coal capacity and tram clearance. 
Classic shuttle car design philosophy has provided for 
operator needs as a secondary consideration, which 
partially explains the limited success achieved over decades 
in developing adequate protective cabs for thin-seam 
shuttle cars. 



PROJECT EXECUTION 



The failure of past design methods to produce adequate 
thin-seam shuttle car cabs required that a fresh approach 
be taken. Thus, the objective of this project was to 
develop an acceptable cab-shuttle car design by giving the 
operator's needs equal priority as related to classic design 
criteria. Although the resulting design could have 
diminished performance specifications compared with 
present designs, a suitable compromise was achieved 
among operator safety, coal-carrying capacity, and 
maneuverability. 

A wide variety of ideas and influences were considered 
to generate cab-shuttle car concepts and guide the 



progression of the project. Therefore, a project advisory 
committee was formed of Bureau and MSHA personnel. 
MSHA participation ensured contributions to the project 
and updated the agency on developments of interest. 

The advisory committee functions were to formulate 
criteria for evaluating the acceptability of cab-shuttle car 
concepts; conceive cab-shuttle car concepts; evaluate, 
refine, and eliminate concepts; and make recommendations 
for future project efforts. 



EVALUATION CRITERIA 



An initial task was the formulation of criteria for 
gauging the acceptability of cab-shuttle car concepts. Two 
classes of criteria were developed: those considered 
mandatory—not meeting them would cause a concept to be 
rejected outright; and those considered desirable-concepts 
including them would be ranked higher than those that did 
not. 

Italic numbers in parentheses refer to items in the list of references 
at the end of this report. 



Mandatory criteria were 

1. The cab should employ protective operator 
structures; this includes protection from ground falls and 
the minimization of pinching and squeezing-type accidents, 
which are the most common in thin-seam shuttle car 
haulage (3). 

2. The cab-shuttle car should be maneuverable in 
workings having typical dimensions for thin-seam room- 
and-pillar mining. 



3. The operator should have adequate field of vision to 
key points on the machine and in the mine. 

4. The operator should be provided a comfortable 
working position. 

5. Other section workers should not be endangered by 
haulage vehicle operation. 

6. Cab ingress and egress should be reasonable. 

7. The cab-shuttle car should be usable in working 
heights down to 40 in. 

The decision was made to target a 40-in working height 
for the cab-shuttle car design, based on the following 
factors: 

A. For the development to be viewed as significant, it 
should be applicable below the current 42-in limit where 
Federal regulations mandate cabs and canopies. 

B. Present industry practice considers 36-in working 
heights as the low cutoff point for batch-type haulage; 
lower height mines generally use continuous haulage. 

C. Previous studies showed a general dislike for low- 
height operating positions other than the semireclined, 
which is usable down to about 40 in for high-speed face 
equipment (4). 

D. The development effort could be approached with a 
reasonable degree of confidence for a successful outcome. 

Desirable criteria included 

1. Ideally the operator should not be required to 
change seat positions depending upon the travel direction. 
In low working heights, changing seats is currently the only 
successful method of obtaining vision in both travel 



directions. However, the procedure is cumbersome, 
awkward, time consuming, and exposes the operator to 
additional hazards. 

2. Cab concepts should be as compatible as possible 
with commercially available shuttle cars. 

3. Cab concepts should be adaptable to haulage 
vehicles other than shuttle cars. 

4. Electronic sensory aids should be employed, but 
kept as simple as possible. For example, a closed-circuit 
television system (CCTS) could provide information on 
blind spots not within the operator's line of sight. 

5. The operator should be provided an indication of 
obstacles in the vehicle path. 

6. For cab designs where it is necessary for the 
operator to change seat positions according to the travel 
direction, the controls should be miniaturized to the point 
of being a hand-held module. The module should be 
connected to machine actuators through either a tethered 
or radio remote control link. This would eliminate the 
need for two separate control panels. 

7. The resulting design should be cost effective. 

8. The controls and cab layout should give the operator 
a feeling of confidence, allow easy operation, and provide 
a natural control sequence. 

9. The complexity of the design should be minimized 
to reduce maintenance frequency. 

10. Floating cabs should be utilized. Past Bureau 
projects (2, 3-4) indicated that floating cabs generally 
provide more operator space than traditional fixed cabs. 



CAB-SHUTTLE CAR CONCEPTS 



Cab-shuttle car concepts were generated at monthly 
meetings held by the advisory committee, and were quickly 
critiqued through open discussions. Those concepts that 
survived the oral discussion stage were translated into 
sketches and/or scale drawings. Most drawings referenced 
concepts to the outline of a National Mine Service* model 
MC28 shuttle car in a typical 40-in working height entry; 
this was considered typical of the 1,839 shuttle cars 
currently in use in coal seams under 48 in. At subsequent 
meetings, the concepts underwent further evaluation, 
discussion, and refinement. Many concepts were 
eliminated through this process; other new ideas were 
conceived and entered the system. 

The generated concepts fell into five general cab-shuttle 
car configuration: 

Reference to specific products does not imply endorsement by the 
Bureau of Mines. 



1. Traverse, center-driven cab: The operator cab is 
situated perpendicular to the longitudinal axis of the 
haulage vehicle, midway between its ends. An advantage 
is that the operator would not have to change seat 
positions when the travel direction changes. Disadvantages 
include that the cab would decrease the coal-carrying 
capacity and the operator would not have excellent field of 
vision in either direction of travel. 

2. Parallel, end-driven cab: The operator cab is situated 
parallel to the longitudinal axis of the haulage vehicle, 
close to one end of the machine. Assuming the operator 
changes seat positions depending on travel direction, this 
configuration would provide the operator with very good 
direct vision in one travel direction, but poor direct vision 
in the opposite direction. Assuming the operator remains 
in one seat position for both travel directions an 



automated steering system or the ability to steer the 
vehicle from sensory input devices would be required. 

3. Parallel, center-driven cab: The operator cab is 
situated parallel to the longitudinal axis of the haulage 
vehicle, midway between its ends. Assuming that the 
operator changes seat positions with travel direction and 
the cab width could be approximately 10 in greater than a 
standard cab, visibility along the side of the machine could 
be adequate, but somewhat impeded by machinery in the 
field of view. When considering a design where the 
operator sits in only one position, direct visibility in one 
travel direction would be nonexistent, requiring the 
addition of remote sensory and/or automated steering 
systems. 

4. Transverse, end-driven cab: The operator cab is 
positioned at an end of the vehicle, perpendicular to the 



longitudinal axis of the machine. An advantage is that the 
operator would have extremely good field of vision when 
tramming to the dump site and restricted, but adequate, 
field of vision in the opposite tram direction. Perceived 
problems included a significant loss of coal-carrying 
capacity, potential roofing-out problems, and the cab and 
chain conveyor mechanism competing for the same space. 

5. Cross-car, end-mounted cab: The operator is 
positioned across the end of the vehicle, perpendicular to 
the longitudinal axis of the chain conveyor. This 
arrangement would give the operator unobstructed vision 
when tramming to the dump site and very good vision 
down the empty conveyor when tramming to the face. The 
main disadvantage appeared to be increased complexity of 
operation when unloading coal. 



DETERMINATION OF REMOTE VISION LIMITATIONS 



The committee initially considered cab-shuttle car 
concepts using conventional parallel, center-driven and 
parallel, end-driven cab placements. Exploration of these 
concepts readily revealed a primary objection to the use of 
protective cabs in low coal - the problem of direct operator 
vision to key reference points. 

If the desirable feature of maintaining the operator in 
one seat position is assumed, both versions of parallel cabs 
considered do not allow the operator direct vision in one 
travel direction. A simple CCTS was proposed to provide 
the operator with visual input from the blind travel 
direction. 

A quick experiment was conducted to estimate an 
operator's ability to steer a vehicle using only CCTS vision. 
The experiment utilized available closed-circuit video 
equipment and a battery-powered vehicle; it took place on 
vacant roadways at the Bureau's Pittsburgh {PA) Research 
Center. A camera transmitted a forward view, in the 
travel direction, to a video monitor placed in front of the 
driver. A shroud prevented direct forward vision. Five 
different drivers attempted to negotiate straight and curved 
road sections using only visual information from the 
monitor. The results of the experiment were not 
favorable. The consensus was that satisfactory movement 



in a desired path required great concentration and could 
be achieved only if an object was present to sight along, 
such as a curb. Poor performance using the video system 
was attributed to the lack of depth perception and 
differences in field and angle of view between a person's 
eyes and the camera lens. 

This experiment was conducted with the drivers trying 
to maneuver the vehicle while facing the travel direction. 
For the concept to be usable with the cabs, the operator 
would need to maneuver the vehicle while facing in the 
direction opposite of travel, further decreasing the 
likelihood of success. 

The negative experiment results led to the following 
conclusions on design options related to parallel-oriented 
cabs: 

1. The operator must switch seat positions, depending 
upon travel direction, which is undesirable. 

2. If the same seat position is maintained, steering the 
vehicle in one travel direction requires additional sensory 
input to supplement televised views, such as obstacle 
detectors, and distance-alignment sensors, and/or that an 
automatic or semiautomatic steering system be employed. 



DISCUSSION OF CONCEPTS 



Although the cross-car, end-mounted cab configuration 
initially appeared to present inherent, insurmountable 
problems, a variation of it was ultimately selected for the 
recommended cab-shuttle car design. The following 
discussion details specific ideas considered for the five 
general cab-shuttle car configurations, reasons for 
dismissing or not selecting the concepts, and the 
preliminary design of the selected configuration. 

1. Transverse, center-driven cab: This configuration 
was successful on a shuttle car used in high seams (5) and 
initially appeared promising for thin-seam application. 



However, drawing the concept to scale revealed there was 
insufficient vertical space for it to be used in a 40-in 
working height. The basic problem was that the operator's 
feet must extend under the conveyor, using 18 in of vertical 
space, and the remaining space was insufficient for the 
conveyor and machine-to-roof clearances. The concept 
was eliminated on these grounds. 

2. Parallel, end-driven cab: Two concepts were 
proposed and evaluated for this cab-shuttle car 
configuration: A, the operator changing seat positions 



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Tram motor 



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FIGURE 1. -Parallel end-driven shuttle car. 



depending on travel direction (fig. 1), and B, the operator 
maintaining one seat position. 

A. The first concept would provide the operator 
with very good direct vision in the travel direction away 
from the machine. Travel in the opposite direction would 
require major changes to the classical layout of shuttle car 
subsystems for increased direct vision and probably 
necessitate that CCTS's be employed to provide views to 
blind spots. 

B. Because of the results of the remote vision 
experiment, the second concept would require additional 
sensory input supplement televised views and/or an 
automatic or semiautomatic steering system. As neither 
concept appeared particularly attractive, they were not 
taken beyond the discussion stage. 

3. Parallel, center-driven cab: The center-driven 
concepts (fig. 2) did not impose length restrictions on the 
cab, thus providing the potential for maximum operator 
comfort. Two concepts on opposite ends of the 
technological spectrum were considered for this cab-shuttle 
car configuration. 

A. The low-technology concept required that (1) the 
operator switch seat positions depending on the travel 
direction, (2) the cab width be approximately 10 in greater 
than current practice, (3) the normal layout of vehicle 
subsystems undergo significant changes to increase 
operator visibility, and (4) CCTS's be employed to improve 
visibility of otherwise blind areas. It was decided not to 
proceed with the development of this cab as it met few of 



the desired design criteria and did not appear applicable 
to a large cross section of the haulage vehicle population. 

B. The high- technology cab concept included the 
following design features: 

1. The operator would sit in one position only, 
regardless of travel direction, and be provided a positive 
indication of the current tram direction. 

2. It would be a generic box, adaptable to a 
wide range of currently manufactured haulage vehicles. 

3. An updated version of the automatic steering 
technology developed by the Bureau would be employed 
(6). This subsystem would output to a display of the 
vehicle's position relative to idealized paths for both 
straightaway tramming and the turning of crosscuts. The 
steering system could be placed in either manual or 
automatic mode. 

4. Wide-angle-view CCTS's would be used, 
providing the operator with views of obstacles in the 
vehicle path. 

5. Electronic rangefinder units would be placed 
on both ends of the vehicle and would output to a cab 
display the distances between the vehicle and objects in the 
vehicle path. 

6. If possible, machine controls would be 
designed to be detachable from the body of the haulage 
vehicle. During emergency situations, this would allow 
remote, within-sight control. 



no 



-307 



■ 50" »T« 60"- 



Cable reel 



108- 



Conveyor motor 



Control case 



89- 



Tram motor 



Pump motor 



32" 



-67"- 



Tram motor 



* * * »y ■#. a 



92 



43" 








FIGURE 2.-Parallel center-driven shuttle car. 



The concept met many of the desired criteria including 
the capability of being placed on many currently 
manufactured haulage vehicles or completely new designs. 

Concept disadvantages included that it would be 
electronically complex, requiring an updated version of the 
automatic-steering technology, wide-angle-view CCTS's to 
provide the operator views of obstacles in the vehicle path, 
and electronic rangefinder units to indicate distances to 
objects. However, the main concern was the unproven 
ability of an operator to maneuver the machine, with no 
direct vision, when traveling in the direction opposite from 
the faced position. 

It was concluded that although the high-technology 
concept did offer merit, it would be best pursued as a 
separate, future project. 

4. Transverse, end-driven cab: This concept (fig. 3) 
worked well on higher seam vehicles because the operator 
was able to tram in both directions without changing seat 
positions. However, this configuration posed several 
serious problems for low-seam applications: 

1. The coal-carrying capacity of the shuttle car 
would be decreased because the operator's legs require 
18 in of space under the conveyor; and, compared to 
conventional design, the cab would extend an additional 
10 in beyond the machine frame, requiring narrower cars 
for adequate maneuverability. 

2. Field would be poor when tramming to the 
face, requiring the application of complex remote sensory 
input devices and CCTS's. 



3. There would be the possibility of roofing and 
ribbing problems due to the cab position on the vehicle. 

5. Cross-car, end-mounted cab: Three cab-shuttle car 
concepts were conceived and discussed for this 
configuration. The third concept was ultimately selected 
as the recommended concept. All the ideas positioned 
the cab across the end of the vehicle, with the longitudinal 
axis of the conveyor intersecting the operator's body and 
the operator's head positioned for adequate vision down 
the chain conveyor trough. 

A. The first concept positioned the cab at the 
vehicle dump end, outboard of the conveyor drive 
structure. The coal would be discharged using a side- 
dump arrangement. 

Advantages of the side discharge configuration included 

1. The operator would have excellent, direct 
vision when traveling to the dump point. Because no coal 
would be on board, direct vision should be adequate when 
traveling to the face. 

2. The addition of electronic subsystems, 
including CCTS's, could prove desirable, but would not be 
an absolute necessity. 

3. Because of the cab location, vehicles with 
cabs wider than what would normally fit within the entry 
dimensions could be accommodated. Thus, the loss of 
coal-carrying capacity resulting from the installation of the 
side-dump mechanism could be minimized or eliminated. 





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FIGURE 3 -Transverse end-driven shuttle car. 




4. Completely new vehicles probably would not 
be required to accommodate the cabs; modification to 
existing vehicles might suffice. 

Disadvantages identified specific to the side-discharge 
configuration included 

1. The cab would have to be attached to the 
vehicle main frame by a cantilevered I-beam approximately 
11 ft long and 10 in deep. 

2. Because the cab would be attached to the 
vehicle, the ability of the cab to tolerate side loadings 
would be decreased. 

3. A floating cab could not be utilized, resulting 
in a small interior space (fitting a 95th percentile male 
would be very difficult). 

4. The side discharge would require a complex 
boom mechanism involving moving slides and other 
apparatus. 

5. The overall vehicle length would increase 
approximately 40 in and the concept could be used only on 
vehicles having chain conveyors at least 56 in wide. 

6. The operator could be exposed to significant 
amounts of dust and noise during the coal discharge 
process. 

The disadvantages were of such magnitude that this 
concept was eliminated from further consideration. 



B. The second concept would also position the cab 
across the normal boom end of the machine, but would 
eliminate the boom and shorten the conveyor to permit a 
bottom-dump arrangement. This would greatly simplify 
the cab mounting (fig. 4). 

Specific advantages defined for the bottom discharge 
configuration were that 

1. A semifloating cab attachment design could 
be employed which would provide ample interior space for 
a wide range of operator sizes. 

2. A coal discharge boom would not be 
necessary, which would decrease design complexity and 
minimize decreased coal-carrying capacity. 

3. The operator would have excellent direct 
vision when traveling to the dump point. Because no coal 
would be on board, direct vision should be adequate when 
traveling to the face. 

4. The addition of electronic subsystems, 
including CCTS's, could prove desirable, but would not be 
an absolute necessity. 

5. Because of the cab location, vehicles with 
cabs wider than what would normally fit within the entry 
dimensions could be accommodate. Thus, the loss of coal- 
carrying capacity, created by shortening the conveyor to 
accommodate the bottom discharge, could be minimized 
or eliminated. 



Shuttle car 



4 



36" 



Cab 



28" 



Motor 



Feeder -breaker 




FIGURE 4.-Bottom dump shuttle car. 



6. Completely new vehicles probably would not 
be required to accommodate the cabs; modification to 
existing vehicles might suffice. 

Disadvantages identified specific to the bottom 
discharge configuration included 

1. The section dump point would have to be 
significantly modified, either by placing the belt or feeder- 
breaker below ground level or requiring the vehicle to go 
up a ramp (taking an additional 12 in of top would be 
necessary). 

2. The chain conveyor drive motor would have 
to be relocated. 

3. If a ramp was not used, an additional, 
specialized loading machine could be required. 

Disadvantages common to both the side- and bottom- 
discharge configurations, 5A and 5B, included 

1. The overall vehicle length would increase 
approximately 40 in. 

2. Operators could be vulnerable to injury from 
obstacle collisions because of the end-mounted cabs. 
However, the excellent direct vision provided should 
enable operators to avoid obstacles. 

3. The concepts would be limited for use on 
vehicles having chain conveyors at least 56 in wide. 



4. The operator could be exposed to significant 
amounts of dust and noise during the coal discharge 
process. 

5. A potential problem existed in the operator 
being able to see the coal discharged from the miner. 
Assistance from the miner helper or augmented vision 
could be required. 

At this point, the bottom discharge configuration, 5B, 
appeared the most attractive of all the concepts 
considered. It seemed capable of meeting all of the 
mandatory design criteria and most of the desirable 
criteria, including that the operator not switch seat 
positions depending on travel direction. The concept's 
primary disadvantage was that the dump point site would 
require extensive modifications. 

As a result of a wooden mockup fabrication of the cab 
and preparation-evaluation of scale drawings of modified 
dump sites, a third concept based on the cross-car, end- 
mounted configuration was developed. This concept, 5C, 
positioned the cab across what would be the load end of 
a conventional shuttle car, opposite the discharge boom 
(fig. 5). As for the previous concepts, the operator's head 
was positioned to maintain good direct vision through the 
conveyor trough when traveling empty. The idea was to 
employ the same vehicle end for both coal loading and 



Boom 
end 



— 307"- 



110"- 



Tram motor 



Cable reel 



Conveyor motor 



Pump motor 



Power box 



Tram motor 



36" 



iio- 



84" 



— 32 — 
-36— 




FIGURE 5 -Transversely mounted end-cab. 



unloading. This concept required no major modifications 
to either the shuttle car or the dump site. 

Previous Bureau programs had proved mockup 
fabrications to be valuable tools in evaluating and refining 
cab and canopy designs prior to full-scale fabrication. 
Once the cross-cab, end-mounted cab concept was 
determined to be feasible, detailed drawings were prepared 
that allowed the construction of a wooden mockup cab 
fabrication to be used with the bottom-discharge 
configuration, 5B. Because an FMC model 6L shuttle car 
was available and had a conveyor of sufficient 
width to accommodate the cab, it was used for the 
evaluation. 

The 6L shuttle car is intended for use in working 
heights higher than the 40-in target height set for the cab 
development. Therefore, the mockup cab fabrication was 
sized to fit the shuttle car. However, this did not decrease 
the utility of the mockup in determining that the concept 
was feasible; it showed there was ample operator space in 
the cab and indicated that direct vision was even better 
than had been assumed. 

The concept maintained all of the advantages of its 
predecessors and provided additional advantages. 

1. A semifloating cab attachment design was 
employed, which provided ample interior space for a wide 
range of operator sizes. 

2. The operator would have excellent direct 
vision when traveling to the dump point. Because no coal 
would be on board, direct vision down the empty conveyor 
should be adequate when traveling to the face. 



3. The addition of electronic subsystems, 
including video monitors, proved desirable, but would not 
be an absolute necessity. 

4. Completely new vehicles probably would not 
be required to accommodate the cabs; modification to 
existing vehicles might suffice. 

5. The concept could be readily adapted to 
many existing shuttle cars with only limited modifications. 
Examples would be the National Mine Service (EIMCO) 
MC 28 and the FMC 5L shuttle cars. 

6. Exposure to dust and noise problems during 
coal discharge would be eliminated. 

7. No modifications to the off-loading site would 
be required. 

8. The shuttle car could have increased coal- 
carrying capacity, compared with current designs, since 
eliminating the cab on the side of the car would permit the 
use of wider cars in the same size entry. 

Only two potential disadvantages were identified for the 
concept 

1. The operator would have limited direct vision 
for determining the size of the coal pile as the mining 
machine loads the car. However, tests using a mockup of 
the cab were conducted and showed that the direct vision 
could be easily augmented through the use of CCTS's. 

2. The operator must turn the vehicle and then 
travel to the dump site with limited direct vision. This also 



10 



should not be a big problem, since the required travel 
distance would be very short (e.g., 15 ft). 

In order to determine if these two problems could be 
overcome through the use of remote vision assist, a quick 
experiment was performed to determine the suitability of 
this technique. The wooden cab mockup was placed 
adjacent to the FMC 6L shuttle car. A video camera 
aimed at the front of the car was linked to a video monitor 



mounted inside the cab. An operator was placed inside 
the cab and watched the monitor as coal was loaded into 
the shuttle car with a conveyor (fig. 6). The operator had 
no trouble determining when the coal pile was high 
enough to be moved. From this experiment, it was 
determined that the concept with the auxiliary CCTS 
would be a workable design. 



DESIGN CONSIDERATIONS 



During the predesign stage of the compartment- 
machine development, the basic operational requirements 
were defined. Tasks that the machine must be able to 
perform were analyzed in relationship to their importance 
in completing a duty cycle mission. The design was 
considered to be a total systems program to be pursued 
systematically. Components were not designed in terms of 
their individual function but rather in terms of their impact 
on the entire system, which include the needs of the 
machine, the needs of the operator compartment, and the 
needs of the operator. System requirements were defined 
in terms of operational requirements, functions required to 
complete each duty cycle, performance requirements for 
each function, and the relationship between the equipment 
and operator needs. 

The design requirements were broken into separate 
categories. The mandate of the project, to give at least 
equal consideration to the needs of the operator and the 
machine requirements, was maintained at all times 
throughout the design process. 

The following factors were determined important for 
the operator to safely complete a duty cycle: 

1. The primary consideration was that the operator 
always be protected from accidents and possible injury. 
The operator compartment canopy should be substantial 
and located to protect the operator from falls of roof and 
rib. Additionally, the compartment itself should be 
designed to prevent the operator from leaning out and 
being pinched or pinned between the machine frame and 
the roof or rib. 

2. The operator should have adequate direct vision to 
essential elements. The major complaint about low-coal 
canopies is the severe restrictions they impose on operator 
field of view. Therefore, a serviceable design must insure 
optimum field of view in an environment that inherently 
restricts it. Operator visual requirements were broken 
down on a task-by-task basis. For example, during 
tramming, the operator must be able to ascertain the 
relative position of the shuttle car in the roadway, the 
machine velocity, and the relative location of the machine 
in the mine. During loading, the operator must determine 
the rate that coal flows from the tail boom of the miner, 
the relative positions of the shuttle car and the mining 
machine, the height of the tail boom, and the position and 
height of the coal load on the shuttle car. During 
dumping, the operator must determine the status of the 
dump site, the position of the machine relative to the 



dump site, the position of the coal load on the vehicle, and 
the height of the tail boom. Finally, the operator must 
always be able to determine the location of obstacles, 
hazards, and other mine personnel. 

3. The control design layout must be logical and meet 
behavioral expectations of the operator. Control systems 
that are radically different from what people are used to 
or expect tend to induce operator error and confusion. 
Controls should meet the requirements outlined in Society 
of Automotive Engineers (SAE) XJ1314 "Human Factors 
Design Guidelines For Underground Mining Equipment" 
(table 1). These same considerations should be given to 
auxiliary visual displays, auditory displays, and other 
sensory input devices. 

4. Operator comfort must be a primary consideration 
in order to prevent fatigue and the resulting lack of 
attention to the job and its inherent dangers. The 
operator must have adequate room so as not to be 
cramped and confined. This requires a wide enough 
compartment so the operator does not feel restrained. 
Additionally, as the canopy height becomes lower, the 
compartment must become increasingly longer to 
accommodate the operator. 

5. The operator seat must provide operator 
comfort and prevent fatigue. Most original equipment 
manufacturer low-coal shuttle car seating is inadequate, 
proper seating should be padded and equipped with an 
adjustable back (with lumbar support) and an adjustable 
head rest. Specific requirements are that 5th percentile 
female through 95th percentile male operators see over the 
top of the machine frame, and, the seat width be adequate 
for the 95th percentile male (fig. 7). 

6. The compartment design should not impede 
operator ingress and egress. Openings must be free of 
obstacles that may snag the operator's belt, cap-lamp 
battery, and self-rescuer. Two important design features 
can be employed to aid the operator. One is to use as 
many handrails and handholds as are feasible to facilitate 
quick and smooth ingress-egress. Another important 
design consideration involves alternative exits. There are 
situations when the operator must exit in a hurry (e.g., 
roof falls, fire, inundation, etc.). If the main egress route 
from the machine is blocked, there should be an 
alternative way out. This alternative escape opening 
should measure, at a minimum, 18 by 30 in. 



11 




FIGURE 6 -Vision-assist test. 



12 



TABLE 1. 


- Recommended control motk 


Control device 


Motion and response 


Foot pedals 


Push to - 




Activate. 




Accelerate (forward). 




Apply brakes. 




Turn on or off. 




Engage a function. 




Release to - 




Deactivate. 




Decelerate. 




Release. 




Disengage. 




Push to- 




Move forward. 




Increase. 




Lower. 




Activate. 




Pull to- 




Stop. 




Move backwards. 




Brake. 




Raise. 




Push to engage-disengage. 


Rotary switches . . . 


Turn clockwise to increase. 


Toggle switches . . . 


Push up to - 




Select a function. 




Activate. 




Push down to deactivate. 


Emergency cutoff . . 


Push to deactivate. 


Cranks or wheels . . 


Turn (clockwise) to - 




Start. 




Increase speed. 




Turn right. 



7. Where necessary, auxiliary sensory inputs to the 
operator should be provided. Because of the extremely 
confined space in a low-coal operator compartment, it is 
highly unlikely that an operator can directly perceive all of 
the information desired to safely control the vehicle 
operation. For maximum efficiency, the operator should 
have direct vision to as many important visual attention 
locations as possible. Auxiliary sensory inputs should 
provide the operator information on blind spots that 
cannot be directly viewed or otherwise perceived. 

8. The operator compartment-shuttle car must be 
designed for the extremes rather than the average 
operator. Efficient operation requires that each operator 
be perfectly positioned, allowing performance of the 
required tasks with a minimum of stress. To 
accommodate the majority of users, a good design provides 
adequate space for a comfortable operating position and 
places controls within easy reach for a 6-ft 3-in male 
dressed in mining clothes with hardhat, cap lamp, and self- 
rescuer. 

The requirements for the machine to successfully 
complete its mission duty cycle require equal 
consideration. Any design would be useless if the primary 








Dimensions, In 


5fh-percentile 


95th-percentile 






female 


male 


/ 


Shoulder height 


19.7 


25.7 


2 


Eye-to- helmet top 


6.0 


6.5 


3 


Forearm -hand length 


15.3 


20.2 


4 


Buttock -knee length 


20.5 


259 


5 


Buttock- leg length 


38.0 


46.1 


6 


Back-of-knee height 


14.8 


18.2 


7 


Shoulder breadth 


14.1 


20.1 


8 


Hip breadth 


12.9 


15.4 


9 


Eye height 


26.9 


33.9 


10 


Sitting height 


30.9 


38.4 


II 


Sitting height 
with helmet 


32.9 


40.4 



FIGURE 7.-Coal miner anthropometrics. 



function of the machine could not be efficiently 
accomplished. 

1. The first limitation is the design criteria that the 
cab-machine operate in a 40-in working height coal seam. 
Although previous studies showed that a significant 
number of shuttle cars operate in coal seams between 42 
and 48 in without canopies, due to court-obtained 
variances, the advisory committee decided the project goal 
should be set below the cutoff point of 42 in set forth in 30 
CFR 75.1710. Based on this, a target goal of 40 in was set. 
It was felt that a successful compartment-shuttle car design 
for this seam height would be a significant accomplishment 
and could be approached with a reasonable degree of 
confidence. 

2. The concept should be adaptable, with minimal 
modifications, to as many existing shuttle cars as possible. 
It is realized that to achieve the project goals the final 
design will have to depart from traditional design concepts 
and practices; historically, no one has been able to resolve 
this issue since shuttle cars were introduced into the 
mining industry in the 1930's. However, use of as much of 
the currently available base vehicles as possible will reduce 
costs and increase acceptance in the mining community. 

3. No mining system equipment modifications should 
be required to accommodate the new equipment. Several 
designs were considered that would have necessitated 



extensive modifications to the dump sites and tail boom of 
the miner. However, these would have significantly 
increased the cost of the system and hindered acceptance. 

4. The addition of the cab should cause no decrease in 
coal-carrying capacity. The primary mission of a shuttle 
car is to rapidly carry as much coal as possible from the 
m inin g machine to the dump site. Time studies have 
shown that haulage is the biggest bottleneck in the 



13 



production cycle; a bigger bottleneck would not help a new 
system gain acceptance. 

5. Adequate tram clearance must be provided for the 
shuttle car to efficiently complete its mission. Vehicles 
must be able to achieve maximum operating velocities 
without "ribbing" or "roofing" (striking the ribs or roof) to 
maximize production, maintain a stable workflow, and 
permit safe and efficient operation. 



DESIGN PROCEDURE 



The design concept chosen was a cross-car, end- 
mounted configuration that positioned the cab across what 
would be the load end of a conventional shuttle car, 
opposite the discharge boom. The operator is positioned 
across the end of the vehicle, perpendicular to the 
longitudinal axis of the chain conveyor. This arrangement 
would give the operator unobstructed vision when 
tramming to the dump site and very good direct vision 
down the empty conveyor when tramming to the face. The 
main disadvantage appeared to be increased complexity of 
procedures when unloading coal. The idea was to employ 
the boom end of the vehicle for both coal loading and 
unloading. This would require the operator to back up a 
short distance to the dump site with his or her direct 
vision obstructed by the coal pile. 



The specific design procedures were followed in 
accordance with the experience the Bureau has developed 
in cab design in over a decade of work in this area. The 
transversely mounted, end-cab (TMEC) concept selected 
for further development was analyzed to insure that it 
would meet the previously established performance 
criteria. A technical description of the proposed shuttle 
car cab concept was sent to major U.S. shuttle car 
manufacturers to solicit their comments. The responses 
received were very favorable and encouraging. 

The TMEC concept needed to be refined and finalized 
to better adapt it to existing low-coal shuttle cars. The 
first task was to finalize the design of the basic 
compartment structure (fig. 8). The optimal compartment 



■72' 



-I8"-»| 



i 



2 Typical 



1 



1 — V 



24" 



40" 



A 



A 36" +. 

6" 



3^ Typical 
36"- 



-4 



L 6" 
FIGURE 8-Compartment design. 



28"- 



14 



dimensions were determined to be 36 in wide by 72 in long 
by 36 in high. 

The 36-in width provides an operator with sufficient hip 
room and freedom of movement. This width should not 
interfere with the capability of the shuttle car to tram 
around corners; it is the approximate dimension the 
unused load end of the vehicle can be shortened without 
altering the stock chain conveyor or decreasing haulage 
capacity. The 72-in compartment length provides the 
operator with extra leg room for comfort in a reclined 
seating position. The 36-in canopy height should provide 
ample clearance to prevent roofing in a 40-in coal seam, 
since the operator compartment is designed to be a 
full-floating cab. Canopy support posts were placed as far 
outboard on the operator compartment as possible, so as 
not to interfere with operator field of vision. Finally, all 
corners and edges of the operator compartment and 
canopy were beveled or sloped so the compartment could 
float over or deflect, rather than jam on any roadway 
obstacles. 

Several additional modifications necessary to adapt the 
concept to existing shuttle cars were identified. First, the 
cable reel will have to be moved from the boom end to the 
cab end of the vehicle to prevent running over the trailing 
cable. The boom end of the vehicle will need additional 
reinforcement, since it is now used for both loading and 
dumping. Finally, the cab end of the shuttle car will need 
to be shortened 36 in to facilitate tramming around 
corners. None of these modifications should affect 
operation or decrease coal-carrying capacity, since wider 
shuttle cars can be used in the same width entries with the 
operator cab relocated from the side of the car. 

Design details of the compartment and related 
components (seating and controls) were evaluated using 
several of the Bureau's computer modeling programs. 

The first program used was the crew-station assessment 
of reach (CAR) program; it insured that all the shuttle car 
controls are at optimum reach locations. Numerous 
control layouts (fig. 9) were designed and analyzed. These 
layouts placed the controls within easy reach of all 5th to 
95th percentile operators without interfering with required 
vision. All of the selected controls are small electrical 
units that activate relay-controlled solenoids. This use 
results in considerable space savings within the cab as 
compared with employing conventional, bulky, hydraulic 
valves and associated hoses. The control layout selected, 
after the computer analysis, is shown in figure 10. This 
design provides a control panel that is positioned in front 
of and within easy reach of the operator. It swings out of 
the way to provide easy ingress and egress. 

The second program was the "CAP" crew-station 
analysis program (CAP), which analyzed the 
anthropometric parameters of the cab and checked 
operator vision at predetermined-required visual attention 
locations. This program generates a simulation of the 
operator field of vision from within the shuttle car to 
predetermined vision points (fig. 11). These points are 
then weighted and compared to a list of required visual 
attention locations established from previous Bureau 



Swing away 
control box bracket 



Monitor 

/-Multifunction 
joystick 




Control box 



Power - 



Swing away 
control box bracket 




Control box 



Multifunction 

joy stick - 



Modular 
control box 



Monitor 




FIGURE 9.-Control layouts. 



15 



programs. The TMEC provided field of vision superior to 
even the operator compartments without canopies now in 
use in low-coal seams. 

The next component to be designed was the seat for the 
shuttle car operator. Because of the limited confines of 
low coal, the operator must be as comfortable as possible 
in order to effectively perform for an 8-h or longer shift. 
After careful consideration, a seat designed under a 
previous Bureau project was selected. This seat (fig. 12) 
permits the operator to sit in the required reclined 
position. Important features include lumbar support and 
an adjustable back to permit smaller operators to sit in a 
more upright position. The seat pad is 15 in long, 22 in 
wide and has an adjustable tilt. It is short enough to 



Swing away 
control box bracket 



Monitor 



Orbital 
steering 




Control box 



FIGURE lO.-Selected control layout 



prevent cutting off circulation in the legs and wide enough 
to provide adequate hip room. Another important feature 
is an adjustable, preshaped support; it holds the head and 
neck in a comfortable, upright position, allowing protracted 
periods of operation. The entire seat is contoured to hold 
the operator securely, formed of foam padding covered 
with vinyl fabric. An option under consideration is a seat 
belt with a Velcro hook-and-loop fastener, a rigid locking 
belt is not needed but a lightweight, easily fastened belt 
using a Velcro hook-and-loop fastener would help secure 
the operator in the seat when tramming over rough 
bottom. 

Previous testing had determined that auxiliary vision 
assist would be necessary. The final design employs the 
most favorable and cost-effective solution -it allows the 
operator direct vision to as many of the required visual 
attention locations as possible. Direct vision is 
supplemented by providing visual input at the blind spots 
through the use of a simple CCTS. The CCTS provides 
visual assistance for those reference points where the 
operator requires additional information. The system 
provides an overlap of direct and transmitted vision so that 
(1) the operator is given a point of reference between 
direct view of an object and the view of the same object on 
the monitor, and (2) the operator is given a choice, where 
possible, between the direct and transmitted view of 
objects. 

The final system consisted of one closed-circuit camera 
enclosed in a protective, explosion-proof housing mounted 
on the boom end of the shuttle car, and, one black-and- 
white monitor located inside the operator compartment. 
It was determined that only two areas required vision 
assistance: a view of the coal flowing from the boom of the 
continuous miner and a view of the dump site when 
backing to it. Therefore, a two-position rotary actuator 
was selected to pan the camera 90°; no camera tilt was 
deemed necessary. 




FIGURE 11. -Computer-generated field of vision. 



16 




FIGURE 12.-Shuttle car operator seat. 



MOCKUP AND EVALUATION 



The mockup and evaluation of a proposed operator 
compartment, prior to the construction of a full-scale 
prototype, has proven to be a useful tool in refining design 
deficiencies and allowing improvements at an early stage 
of the project development. It was decided that, to 
accurately evaluate the proposed operator compartment- 
shuttle car concept, a semifunctional mockup needed to be 
constructed. The completely unique position of the 
operator compartment, with respect to the shuttle car, 
posed a question as to whether or not an operator could 
effectively control the machine from the cross-car position. 

To construct the working mockup, a steel platform was 
welded to the end of a functioning MC36 shuttle car. This 
served as a base on which to construct the compartment 
mockup. The available shuttle car was not a low-coal 
shuttle car, having a 36-in frame height. Therefore, the 
base plate was positioned 16 in above the ground to 
simulate the spatial and visual conditions the operator 
would perceive when the compartment was installed on a 
shuttle car with a 28-in frame height. The previously 
selected control system layout was installed along with the 
selected operator seat and the CCTS. Fully functional 
steering, brake, and tram controls were employed so that 



the actual feel of driving the shuttle car could be 
evaluated. 

Once the mockup was completed and all systems were 
functioning, a surface evaluation of the system was 
conducted. Several experienced operators trammed the 
shuttle car through a predetermined course; equipment 
performance and operator comments were noted. The 
operator compartment was then evaluated based on the 
previously established project criteria. 

The overall results of the evaluation were encouraging. 
After a brief practice period to orient themselves to the 
new system, the operators were able to maneuver the 
shuttle car through the course with comparative ease. 
Operator comments primarily centered on a dramatic 
increase in field of vision and space when comparing the 
new design to traditional shuttle car operator 
compartments. Operator ingress-egress was accomplished 
with relative ease, and the seating was easily adjusted to 
accommodate all operators. In general, the proposed 
operator compartment-shuttle car concept appeared to be 
a feasible and efficient solution to the difficult problem of 
providing protection for thin-seam shuttle car operators. 



17 



CHANGES RESULTING FROM MOCKUP 



Although primarily successful, the evaluation identified 
several improvements that should be incorporated in the 
control layout. These improvements were to better 
accommodate a 95th percentile male operator. The swing- 
away control panel located in front of the operator 
enhanced ingress-egress for most operators, but tended to 
hit the legs of very large operators. Therefore, the 
decision was made to place the operator controls in a 
more traditional location on the side of the operator 
compartment. This arrangement does not provide the 
same ease of reach to the controls, but is satisfactory and 
does permit the accommodation of a greater segment of 
the operator population. 

The second improvement was to modify the standard, 
orbital steering unit used to maneuver the shuttle car. 
Previous experience with the anthropometric design of 
steering units had shown that positive directional steering 
(where the shuttle car turns right when the wheel is turned 
clockwise and left when the wheel is turned 
counterclockwise) is the most desirable design philosophy. 
However, for some operators, it did not always function as 
expected for this unique situation. The design does not 
require the operator to change seating positions according 



to the direction of travel. Based on learned behavior from 
driving an automobile, an operator's performance 
expectation could be that the steering direction would be 
opposite when traveling in the opposing directions. Since 
this was a problem for some operators, it was assumed 
that changing the steering to a nonpositive pattern could 
cause problems for the operators that had adjusted to the 
original system. The solution was to convert the standard 
orbital steering, through the use of a gearing mechanism, 
into a joystick-type steering (fig. 13). This new system 
steers the car to the right whenever the joystick is pushed 
to the right and vice versa regardless of tram direction. 

Once these modifications were incorporated into the 
compartment mockup (fig. 14), the evaluation trials were 
repeated. Since the new steering system had no 
conceptional relationship with an automobile, all operators 
readily adapted to the redesigned steering and were easily 
able to maneuver the shuttle car in either tram direction. 
The second set of trials went smoothly with no perceivable 
major problems remaining. The compartment design now 
appears ready for full-scale fabrication and test of proof- 
of-concept. 




FIGURE 13.-Joystick steering. 



18 




FIGURE 14.-Final mockup. 

CONCLUSIONS 



From the work completed, it appears that the Bureau 
of Mines TMEC concept for a operator compartment- 
shuttle car is a feasible and safer solution to the problem 
of implementing protective operator structures on low-coal 
shuttle cars used in 40-in working heights. The developed 
concept provides good operator protection from the 
hazards of roof falls and eliminates the possibility of 
pinching-squeezing accidents (responsible for 90 pet of all 
shuttle car accidents). The concept overcomes the primary 
objection to canopies -the lack of direct vision. Its unique 
location on the shuttle car takes advantage of the empty 
conveyor to provide the operator with a direct line of sight 
to the vast majority of required visual attention locations. 
The design also provides the operator with ample space 
for comfort. Additionally, this concept meets all of the 



design criteria established by the project advisory 
committee. 

It is anticipated that the project will continue through 
the fabrication of a full-scale prototype for proof-of- 
concept underground evaluation. Future work will include 
the fabrication of a generic compartment that can be 
adapted to an existing shuttle car and the detailed 
specifications for a shuttle car incorporating the concept. 

Specific tasks should include fabrication of a generic 
compartment and all related hardware. A compartment 
should be constructed that can be adapted to a modified 
low-coal shuttle car when one becomes available. All of 
the control systems and hydraulic modifications should be 
constructed and tested on a currently available high-coal 
shuttle car to verify correct function and suitability. 



REFERENCES 



1. Bartels, J. R, A. J. Kwitowski, W. D. Mayercheck. Protective 
Structures for Low-Coal Shuttle Car Operator. BuMines RI 9143, 1987, 
22 pp. 

2. Kramer, J. M. (Mine Safety and Health Administration, 
Pittsburgh, PA). Personal Communication, Aug. 1986; available upon 
request from A. J. Kwitowski, BuMines, Pittsburgh, PA. 

3. Lindahl, P. D., and K L. Whitehead. Cost Benefit Analysis of 
Low-Coal Cabs and Canopies, (contract J0199005, Bituminous Coal 
Res.). BuMines June 1982. OFR 124-85, Nov. 1983, 144 pp.; NTIS PB 
86-138930. 



4. Kwitowski, A. J., and R J. Gunderman. Development of a 
Protective Operator Compartment for a Thin-Seam Mobile Bridge 
Carrier. BuMines IC 9093, 1986, 27 pp. 

5. Mantel, J. Development and Assessment of New and Existing 
Canopy Technology to Lower Coal Seams, (contract H0387026, ESD 
Corp.). BuMines OFR 7-86, June 1985, 101 pp. 

6. Troyer, M. Test Program for Automatic Steering Shuttle Car. 
Final Report (contract J0155048, Bendix Corp.). BuMines OFR 51(1)- 
77, 1976, 73 pp.; NTIS PB 265 178. 



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